An Investigation into the Security of Self-Timed Circuits

Self-timed logic may have advantages for security-sensitive applications. The absence of a clock, as a reliable timing reference, makes conventional power analysis attacks more difficult. However, the variability of the timing of self-timed circuits is a weakness that could be exploited by alternative attack techniques. This paper introduces a methodology for the differential power analysis of self-timed circuits which does not rely upon a clock signal. This methodology is used to investigate the security of a self-timed, ARM-compatible processor designed specifically to explore the benefits of self-timed design in secure applications. Timing analysis is also applied to the same design. The results from the analyses are presented and confirm that self-timed logic with dual-rail encoding and secure storage significantly improves resistance to non-invasive attacks.